Determination of the efficacy of preservation of non-eye area water-miscible cosmetic and toiletry formulations: Collaborative study

A collaborative study was conducted to test a method developed to distingui sh between adequately and inadequately preserved cosmetic formulations, Nin eteen laboratories participated in the study, Samples tested included shamp oos, hair conditioners, oil-in-water emulsions, and water-in-oil-emulsions. Triplicate samples of 4 adequately preserved and 4 inadequately preserved cosmetic products were tested by each collaborative laboratory. Results sho wed that all inadequately preserved shampoo and conditioner samples failed to meet the acceptance criteria for adequately preserved formulations. Of t he 51 preserved samples, 49 shampoos and 48 conditioners met the criteria f or adequate preservation. All samples of inadequately preserved water-in-oi l emulsions and oil-in-water emulsions failed to meet the acceptance criter ia, whereas all adequately preserved emulsion formulations met the acceptan ce criteria.